Re: [PATCH v4 4/7] KVM: VMX: Implement LASS violation check

[Sohil Mehta <sohil.mehta@intel.com>]

> 
> This looks like an essential piece for the check introduced in the 
> series. I could follow the logic, and it looks sane to me. If allowed,
> 
>    Reviewed-by: Chang S. Bae <chang.seok.bae@intel.com>
> 

Thanks!

> The code also looks to be written according to Sean's comment in:
> 
>    https://lore.kernel.org/kvm/ZNwOYdy3AC12MI52@google.com
> 

Yes, that's exactly the reason I didn't modify it much. But 3 years is a
long time. So Sean's preference may have changed.

> Yes, this could be a matter of taste as taking and going to maintain the 
> code. But as a reader looking at this, the logic was not that easy to 
> capture at a high level.
>

At first look, I found it a bit hard to follow as well. But instead of
splitting out the logic into 4 static functions (which have limited
value to the rest of the file), how about we add a high level comment on
top of the function?

I'll let Sean comment whether he prefers to change anything here or
leave it as-is.

Note, some function names in the proposed diff could be misleading. For
example, is_user_mode() checks the IMPLICIT flag in addition to the CPL
which feels odd. And, is_lass_enforced() seems like a generic LASS check
but in reality it only covers the supervisor data rule.